The present invention relates to a new and improved construction of mold for a continuous casting installation, and in particular concerns a steel continuous casting mold for billets and blooms having a cross-sectional shape possessing corners, preferably a four-cornered cross-section, which mold is of the type comprising an upper mold part and a lower mold part, walls of the lower mold part which are movable independently of one another are arranged to be movable about pivot shafts or equivalent structure defining pivot axes which extend transversely with respect to the direction of travel of the cast strand and are operatively connected with the upper mold part, these mold walls being movable in the direction of the hollow cavity or compartment of the mold by the action of springs or other suitable resilient elements.
During the continuous casting of steel, especially at high casting speeds, it is of utmost importance for the strand upon departure from the continuous casting mold to have a uniform and as thick as possible strand shell or skin.
Due to contraction of the strand shell within the mold such shell or skin moves away from the mold walls, or depending upon the cross-section of the strand and the taper of the hollow cavity or compartment of the mold, produces an irregular contact of the strand at the mold walls over the circumference of such strand. Due to such irregular strand contact there is formed, especially at the lower part of the mold, a strand shell or skin which, at the exit end of the mold, especially at the regions of the corners, possesses different thicknesses and can lead to known flaws in the cast product, such as rhomboidness, fissures and so forth, and even can result in metal break-out.
There is already known to the art a continuous casting mold for casting strands having four corners, this mold comprising a mold upper part and a mold lower part. The mold lower part is constructed of four walls which can be moved independently of one another, each wall being movable about a pivot or tilt shaft arranged transversely with respect to the direction of travel of the strand and operatively connected with the upper mold part. By means of springs the walls are applied at a predetermined force in the direction of the hollow cavity or compartment of the mold. During a tilting movement of the wall, and viewed with respect to the direction of strand travel, there are produced different displacement paths for each point of the guide surface of the wall directed towards the strand. With changing cross-sectional dimensions of the strand at the outlet or exit end of the upper part of the mold, as such arise during a pour with changing casting speed and/or casting temperatures as well as irregular cooling due to shrinkage and so forth, there is not ensured with such prior art construction contact of the wall the strand over its entire length. Hence, there results irregular wear of the walls, irregular strand cooling with attendant strand defects, and irregular shell or skin thickness of the casting which can lead to rhomboidness of the cross-section of the cast strand, fissures, metal break-out and so forth. The aforementioned drawbacks preclude increasing the casting speed above the usual value of about three meters per minute for a cross-section of 100 .times. 100 mm.sup.2.